1. Field of the Invention
The present invention relates to a process to generate a skew table for a head of a hard disk drive.
2. Background Information
Hard disk drives contain a plurality of magnetic heads that are coupled to rotating disks. The heads write and read information by magnetizing and sensing the magnetic fields of the disk surfaces. Each head is attached to a flexure arm to create a subassembly commonly referred to as a head gimbal assembly (“HGA”). The HGA's are suspended from an actuator arm. The actuator arm has a voice coil motor that can move the heads across the surfaces of the disks.
Information is typically stored in radial tracks that extend across the surface of each disk. Each track is typically divided into a number of segments or sectors. The voice coil motor and actuator arm can move the heads to different tracks of the disks between the inner and outer diameters of the disks.
The tracks have servo information that is used to center the heads relative to the tracks. The heads typically have a write element for writing information and a separate read element for reading information on the disks. The read element is typically offset from the write element relative to the center of a track. Consequently, centering the read element will not necessarily center the write element and vice versa. The offset will vary for different radial positions of the disks.
Some disk drives have a skew table that contains offset values for various radial disk positions. The offset values in the skew table are used to adjust the position of the heads to center the read and write elements. The skew table is generated by measuring the offset at different radial positions. Offset values for non-measured radial positions are interpolated from the measured values. As track densities increase more measured offset values are required to generate an accurate skew table. Taking more measurements increases the time required to generate the skew table and the overall time to manufacture disk drives. An increase in process time decreases production efficiency for mass producing hard disk drives. It would be desirable to minimize the time required to generate a skew table.